The present invention relates to a disc cartridge, and more particularly to a disc cartridge which has a hard disc, especially a double-sided type hard disc, housed in a casing.
In general, a disc-type data recording carrier such as a compact disc (CD), a video disc (LD) or the like is used in a manner of being removed from a packing case and set in recording and/or reproducing equipment such as a disc player.
Conventionally, it has been highly desirable to protect such a disc-type recording carrier from the environment, because it is not only easily covered with dust and damaged, but adversely affected due to variation in temperature. For this purpose, a disc cartridge has been proposed which is adapted to house or receive a disc in an envelope such as a tray, a casing or the like, to accomplish protection of the disc. Such an envelope is so constructed that a shutter for actuating a window through which a head of a disc player is inserted therethrough into the envelope, is opened when a disc is to be operated and closed when it is not used.
However, when any unexpected shock is applied to the envelope due to, for example, dropping during non-use of the disc cartridge, then the shutter is often suddenly opened, resulting in the functioning of the envelope being deteriorated to a degree sufficient to cause it to become unserviceable. More particularly, the conventional disc cartridge is constructed in a manner such that a shutter lock member for locking the shutter during non-use is actuated in association with a disc actuator. Accordingly, when the disc cartridge is unexpected shocked during non-use, due to dropping or the like, the weight of the disc overcomes a bearing capacity of the disc actuator to actuate the disc actuator, which then actuates the shutter lock member to cause the shutter to become released from the shutter lock member, so that the window is opened, causing dust and the like to readily enter into the disc cartridge therethrough. Unfortunately, the conventional disc cartridge lacks an effective manner of eliminating such a problem except by manual closing of the shutter. However, the manual closing renders handling of the disc cartridge highly troublesome and deteriorates reliability of the disc cartridge.
Accordingly, it would be highly desirable to develop a disc cartridge which is capable of positively preventing a shutter from being opened due to any unexpected shock applied to the disc cartridge during non-use to thereby ensure operation of the disc cartridge with high reliability for a long period of time.